Method measuring transparent elements and an opaque medium

Abstract

In measuring the dots of a color picture tube panel the panel is scanned and energy passing through the dots is detected. A large number of lines are scanned and the scan data are stored in a matrix having a row for each scan line and, columns for the dots and the spaces between the dots. Data for a preselected number of dots and spaces are stored. When scanning occurs between rows of dots, the preselected number of dots is not scanned and zeros are put into the matrix. Data processing is simplified by searching the last column of the matrix for zeros and rejecting all rows of data having a zero in that column.

What is claimed is: 
     
       1. A method of measuring the dimensions of, and spaces between, transparent elements arranged in pattern in an opaque medium including the steps of: (a) placing said medium between an energy source and an array of pixels responsive to said energy and illuminating said medium with said energy;   (b) scanning said energy across said array in a plurality of scan lines whereby pixels receiving energy passing through said transparent elements charge to a first charge level and pixels shaded by said medium charge to a second charge level;   (c) detecting said charge levels and producing an analog signal having amplitude levels indicative of said charge levels and pulse widths indicative of a dimension of said transparent elements and of said spaces between said elements;   (d) converting said analog signal to a digital signal having first and second pulse levels in accordance with said amplitude levels, whereby said dimensions are represented by pixel counts;   (e) transferring said pixel counts for a selected number of said transparent elements, and for an equal number of spaces between said elements, to a storage means, and transferring zeros to said storage means where the number of transparent elements is less than said selected number;   (f) storing said pixel counts in a matrix wherein the pixel counts for each of said scan lines form a row and the pixel counts of said transparent elements and each of said spaces are aligned as columns, one of said columns having a succession of zeros when the number of transparent elements is less than said selected number; and   (g) successively investigating said one column for zeros and rejecting rows having one of said zeros is said one column, and accepting rows having a pixel count in said one column.   
     
     
       2. The method of claim 1 further including the step of investigating said one column until a succession of pixel counts if followed by a plurality of zeros. 
     
     
       3. The method of claim 2 further including the step of disregarding the first n rows having a pixel count in said one column and the last m rows having a pixel count in said one column. 
     
     
       4. The method of claim 3 further including the step of investigating said pixel counts in said rows and using the highest of said pixel counts to identify said dimension of said transparent elements. 
     
     
       5. The method of claim 4 wherein said dimension is identified by high, substantially equal, pixel counts in the same column in at least two successive rows. 
     
     
       6. The method of claim 5 further including the step of measuring the dimension of three light transparent elements in the row containing said high pixel counts, by averaging the pixel counts in every fourth column. 
     
     
       7. The method of claim 6 wherein pixel counts for χ of said transparent elements and, χ of said spaces, are transferred to said storage means and, the pixel count for at least one of said columns is disregarded. 
     
     
       8. The method of claim 7 wherein the first transparent element scanned, and the first space scanned, are disregarded. 
     
     
       9. The method of claim 1 further including the step of investigating said pixel counts in said rows and using the highest of said pixel counts to identify said dimension of said transparent elements. 
     
     
       10. The method of claim 9 wherein said dimension is identified by high, substantially equal, pixel counts in the same column in at least two successive rows. 
     
     
       11. The method of claim 10 further including the step of disregarding the first n rows having a pixel count in said one column and the last m rows having a pixel count in said one column.